JP3906878B2 - Manufacturing method of liquid crystal element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a liquid crystal element having a polymer alignment film.
[0002]
[Prior art]
In a liquid crystal display element, in order to align liquid crystal in one direction at a predetermined tilt angle, a technique that is generally used is to form a polymer material on a substrate surface and then apply the surface to a surface such as rayon. It is a rubbing method that rubs in one direction with a cloth. In addition, by forming a monomolecular film on the water surface and transferring the film to the substrate, the Langmuir-Blodgett method (LB method), which functions as an alignment film, or SiO ₂ , Au, Al, etc., is applied to the glass substrate. On the other hand, there is a method of aligning the liquid crystal by vapor deposition obliquely.
[0003]
However, in the LB method, it is unavoidable to spend a great deal of time for film formation, and the alignment regulating force is not sufficient. In the vapor deposition method, the apparatus is large-scale, and much energy is consumed for producing the alignment film, and the time is greatly consumed as compared with the rubbing method. Therefore, the rubbing method is currently mainly used as a liquid crystal alignment technique.
[0004]
However, in the rubbing method, since the cloth directly contacts and rubs the alignment film surface, static electricity is generated on the alignment film surface, and dust is attached or ions in the liquid crystal are adsorbed when assembled as a panel. This adversely affects the quality of the liquid crystal display element. In addition, when the rubbing method is applied to a liquid crystal display element including a TFT (Thin Film Transistor) element, static electricity generated by friction also destroys the TFT and causes a decrease in yield.
[0005]
[Problems to be solved by the invention]
Therefore, recently, as a liquid crystal alignment technique that replaces this rubbing method, an optical alignment technique that aligns liquid crystals by irradiating organic matter with polarized ultraviolet rays has been developed (JP-A-9-5747, etc.).
[0006]
However, it is not easy to obtain polarized light with a high polarization degree from a light source having a large area and a wavelength in the ultraviolet region. For example, a Grand Taylor prism using natural calcite has a high degree of polarization, but cannot have a large area. In addition, a polarizing element using a dielectric multilayer film has a limited wavelength range in which light can be polarized, and is formed by a vapor deposition method, so that it is difficult to obtain a multilayer film having a large area. Even when a laser that is originally linearly polarized light is used, a process of scanning a laser beam or a substrate is required to align a large area.
[0007]
The objective of this invention is providing the manufacturing method of a liquid crystal element which can produce the polymer liquid crystal aligning film with favorable liquid crystal orientation using the polarization | polarized-light with a sufficiently high polarization degree even if it is large area.
[0008]
[Means for Solving the Problems]
That is, the present invention provides a method of manufacturing a liquid crystal element in which an electrode and a liquid crystal alignment film are respectively formed in this order on opposing surfaces of a plurality of substrates facing each other, and liquid crystal is sealed between the opposing surfaces.
A polarizing element comprising a plurality of light transmitting plate disposed together with a predetermined gap to face the polymer film on the front Symbol electrodes of said substrate,
Of the plurality of light transmitting plates, light is incident at a Brewster angle or almost a Brewster angle from one light transmitting plate side, and polarized outgoing light is obtained from the other light transmitting plate side,
Irradiate the emitted light to the polymer film to form a liquid crystal alignment film,
The a plurality of substrates with a liquid crystal alignment film, the alignment direction so that opposed to so that Do antiparallel with the opposing surface,
In this state, the liquid crystal is sealed
The present invention relates to a method for manufacturing a liquid crystal element .
[0014]
According to the method for manufacturing a liquid crystal element of the present invention, a plurality of light transmitting plates are arranged with a predetermined gap from each other, and light is incident at a Brewster angle or almost a Brewster angle from the side of one light transmitting plate, Since the polarized outgoing light is obtained from the other light transmitting plate side, the ratio of the target polarization component can be increased while the transmission and reflection of the incident light are repeated by the plurality of light transmitting plates. Therefore, incident light can be efficiently polarized, and output light with a sufficient degree of polarization can be obtained even with a large area. By this irradiation of polarized output light, a polymer film with a large area can be converted into a liquid crystal. It becomes possible to process so that it may be in a state sufficient for orientation.
Then, a plurality of substrates with the liquid crystal alignment film subjected to the polarization treatment are arranged to face each other so that the alignment treatment direction is antiparallel to the substrate facing surface, and the liquid crystal is sealed in this state. The liquid crystal molecules can be aligned in a highly ordered manner with a uniform pretilt angle in one direction.
[0015]
By sufficiently controlling the alignment of the liquid crystal in this way, it becomes possible to polarize ultraviolet rays in a large ultraviolet wavelength region of about 200 nm to about 400 nm in a large area and irradiate the alignment film material. In particular, as described later, since the spacers between the quartz plates keep the distance between the quartz plates constant, it is possible to irradiate the alignment film material with ultraviolet rays having a high degree of polarization. The quartz plate absorbs almost no ultraviolet rays, so the transmittance is large, and the loss of irradiation intensity due to polarized light is close to the ideal 50%. With these characteristics, by using this polarizing element as an ultraviolet polarizing device for liquid crystal alignment treatment, irradiation energy necessary for liquid crystal alignment can be obtained in a short time, and the alignment order of the liquid crystal can be increased.
[0016]
The polymer alignment film obtained by the irradiation treatment can align the liquid crystal molecules in one direction with a uniform pretilt angle without performing the rubbing treatment. As a result, the occurrence of static electricity and TFT breakdown, which are problems in the rubbing process, are prevented, and the yield is improved and the productivity is of course improved.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
In the method for manufacturing a liquid crystal element according to the present invention, it is preferable that a spacer is provided between the plurality of light transmitting plates, and the gap is kept constant or substantially constant at least in the light incident region and the light emitting region.
[0018]
In addition, it is desirable that a plurality of quartz plates that transmit ultraviolet rays, particularly artificial quartz plates , are arranged in parallel or substantially in parallel, and unpolarized ultraviolet rays are incident as the light to obtain ultraviolet linearly polarized light.
[0019]
In addition, the light transmitting plate includes a plurality of light transmitting plates arranged with a predetermined gap between each other, and a light source that makes light incident at a Brewster angle or almost a Brewster angle from the side of one light transmitting plate, and the other light transmitting plate. The apparatus is preferably configured to obtain polarized outgoing light from the side of the light plate.
[0020]
Next, a preferred embodiment of the present invention will be described.
[0021]
First, an ultraviolet polarization method and an apparatus (or a polarization element) that are characteristic in the present embodiment will be described.
[0022]
The principle of ultraviolet light polarization uses Brewster's law, which is one of the properties of light. An artificial quartz plate that transmits even ultraviolet rays is used as a material that makes light incident at a Brewster angle.
[0023]
When ultraviolet rays are incident on this quartz plate by tilting the Brewster angle, the S wave is reflected and the P wave is transmitted. Therefore, it is possible to extract the polarized light by entering non-polarized ultraviolet rays. The Brewster angle can be obtained by the following equation. Here, i is the Brewster angle and n is the refractive index of the medium.
tani = n (Formula 1)
[0024]
Since the refractive index of artificial quartz is 1.51 at 237 nm and 1.47 at 404 nm, the Brewster angle is 55.7 to 56.5 degrees from the equation (1). Therefore, when a quartz plate is used for polarized light in the ultraviolet region, it is preferable that the ultraviolet light is incident with an incident angle of approximately 56 degrees.
[0025]
Since artificial quartz has a small imaginary part of the refractive index even in the ultraviolet region near 200 nm and does not absorb light, a polarizing element having a high transmission characteristic with a transmittance of about 50% can be manufactured. In order to increase the degree of polarization, it is effective to increase the number of quartz plates and to stack them through an air layer. This is because each time a plurality of quartz plates are passed through, the S wave component of the incident light is reflected more to reduce the transmission component and only the P wave is transmitted, thereby reducing the S wave component for the P wave component. This is because there is an effect.
[0026]
In order to obtain a high degree of polarization at that time, it is required to maintain parallelism between the quartz plates. This can be easily understood from FIGS. 1 and 2.
[0027]
Only the first quartz plate 8 is arranged so as to be incident at the Brewster angle θ ₁ , and the second quartz plate 10 facing (stacking) the first piece 8 through the air layer 9 is the first piece. First consider the case that is not parallel to.
[0028]
As shown in FIG. 2, when unpolarized ultraviolet light 1 including an S wave indicated by ● and a P wave indicated by-is incident on the quartz plate, a slight amount of S wave (this is Smaller P-waves including ● are also transmitted. When the transmitted ultraviolet light 1 </ _b > A is incident on the second quartz plate 10, the incident angle θ ₂ is different from the Brewster angle because the second quartz plate 10 is not parallel. As a result, the S wave passes through the second quartz plate 10. Further, when the ultraviolet ray 1B ′ reflected on the surface of the second quartz plate 10 and further reflected on the back side of the first quartz plate 8 and entering the surface of the second quartz plate 10 is considered. Since the incident angle θ ₃ is also different from the Brewster angle, the S wave is transmitted.
[0029]
Thus, in the case where the quartz plate 10 is not parallel to 8, there is a high possibility that the S wave will be transmitted, and the degree of polarization of the resulting outgoing ultraviolet rays 1C ′ and 1D ′ will be significantly reduced. .
[0030]
Compared to this, consider the case of a polarizing element in which spacers are arranged between quartz plates.
[0031]
As shown in FIG. 1, since the two quartz plates 8 and 10 are supported by the spacers 4 of the same size, the gap is kept constant (that is, the quartz plates 8 and 10 are parallel). . In addition, since the incident angle θ ₁ of the ultraviolet ray 1A directly incident on the surface of the second quartz plate 10 and the ultraviolet ray 1B incident by multiple reflection is a Brewster angle, the S wave can be transmitted at all ideally. The polarization degree of the obtained outgoing ultraviolet rays 1C and 1D is remarkably increased.
[0032]
Thus, it can be understood that an ultraviolet polarizing element having a high degree of polarization can be produced by arranging the multilayered quartz plates 8 and 10 in parallel.
[0033]
Therefore, in order to hold a plurality of quartz plates at equal intervals, a spacer 4 is dispersed between the quartz plates, and then both quartz plates are overlapped, and these quartz plates are combined, whereby a polarizing element 5 having a high degree of polarization. Can be produced.
[0034]
An example of manufacturing this polarizing element will be described. First, a spacer 4 having a diameter of 10 μm is sprayed on a quartz plate (for example, 10) having an area of 10 cm × 10 cm and a thickness of 1 mm using a dry spacer spraying apparatus for manufacturing a liquid crystal display. The amount of spacers to be dispersed at this time may be a minimum amount to be applied to hold the two quartz plates at regular intervals. This is because when the amount of application is large, the transmittance of ultraviolet rays is lowered.
[0035]
Next, an ultraviolet curable resin containing a spacer having a diameter of 10 μm is disposed around the quartz plate with a dispenser. Next, a second quartz plate is placed on the quartz plate on which the spacers are dispersed, and the two quartz plates are pressurized to make the gap uniform, and then bonded by irradiating with ultraviolet rays. . This process is similar to the technique for overlaying substrates of liquid crystal display elements.
[0036]
Thereafter, the quartz plates are stacked one after another, and the stacking of 20 sheets is completed to complete the quartz polarizing element. The short side of the effective area of this polarizing element is approximately 5.6 cm since it is obtained by multiplying 10 cm by a cosine of 56 degrees. Therefore, this polarizing element is an element that polarizes a region having an area of 10 cm × 5.6 cm.
[0037]
Next, a specific example of the polarizing element 5, a method for manufacturing a liquid crystal alignment control film using the polarizing element 5, and an apparatus therefor will be described.
[0038]
As shown in FIG. 3, a high pressure mercury lamp 11 is used as the light source. Ultraviolet light 1 emitted from this lamp is converted into parallel light by a collimator lens 2. At this time, the ultraviolet rays are parallel light, but are not polarized. The higher the parallelism of the parallel light, the higher the degree of polarization after passing through the quartz plate. Ideally, it is most preferable if perfect parallel light can be obtained. Polarized light is obtained by allowing the parallel light to pass through the polarizing element 5 in which the above-described quartz plates 8 and 10 (here, each quartz plate is indicated by reference numeral 3) are laminated at regular intervals. It has a high degree of polarization, and transmits ultraviolet light having a low wavelength of 200 nm to ultraviolet light having a high wavelength of 400 nm.
[0039]
Therefore, when used in combination with a bandpass filter or a cut filter in this range, a liquid crystal alignment film can be obtained by irradiating the polymer film 6 such as polyimide on the liquid crystal substrate 7 with only polarized ultraviolet rays having an arbitrary wavelength. . Further, it is possible to irradiate the alignment film with polarized ultraviolet light having an arbitrary wavelength or longer. As described above, by using the quartz polarizing element according to the present invention, it is possible to perform ultraviolet polarization with a high degree of freedom.
[0040]
FIG. 4 shows a configuration example of a liquid crystal display element (cell) manufactured using a liquid crystal substrate with a liquid crystal alignment film manufactured as described above.
[0041]
According to this liquid crystal display element, transparent electrodes (for example, ITO (Indium Tin Oxide)) 20A and 20B are provided on transparent glass substrates 7A and 7B (corresponding to the above 7), and a polyimide film as a liquid crystal alignment film thereon. 6A and 6B (corresponding to 6 above) are formed, and these films are irradiated with polarized ultraviolet rays by the above-described method to form liquid crystal alignment (control) films.
[0042]
The thus-prepared substrate with the alignment film is assembled so that the alignment treatment direction is antiparallel to the opposing surface, and glass beads (true yarn balls) 21 corresponding to the target gap length are used as the spacer. Depending on the size of the transparent substrate, the spacers are dispersed in a sealing material (UV curable adhesive) 22 that adheres the periphery when the area is small, thereby controlling the gap between the substrates. When the substrate area is large, the true yarn balls are spread on the substrate, a gap is formed, a liquid crystal injection hole is secured around the cell, and the cell periphery is bonded with the sealing material.
[0043]
Thereafter, for example, the ferroelectric liquid crystal 23 is injected under reduced pressure in a state where the fluidity of the isotropic phase temperature or the chiral nematic phase temperature is exhibited. After the liquid crystal is injected, the liquid crystal is slowly cooled to remove the liquid crystal on the glass substrate around the injection hole, and then sealed with an adhesive to produce the liquid crystal element 24.
[0044]
As is clear from the above description, according to the method and apparatus of the present invention, a plurality of artificial quartz plates 8 and 10 are arranged in parallel while being held in a fixed gap via the spacers 4, and one quartz plate 8 is arranged. The non-polarized ultraviolet ray 1 is incident from the side of the Brewster angle θ ₁ and the polarized ultraviolet rays 1C and 1D are obtained from the other quartz plate 10 side. The ratio of the desired polarization component can be increased while repeating. Therefore, incident light can be efficiently polarized, and outgoing light with a sufficient degree of polarization can be obtained even with a large area. By irradiation with this polarized outgoing light, a polymer film with a large area is sufficient for liquid crystal alignment. It becomes possible to process so that it will be in a proper state.
[0045]
By sufficiently controlling the alignment of the liquid crystal in this way, it becomes possible to polarize ultraviolet rays in a large ultraviolet wavelength region of about 200 nm to about 400 nm in a large area and irradiate the alignment film material. Further, since the spacer 4 between the quartz plates 8 and 10 keeps the distance between the quartz plates constant, it becomes possible to irradiate the alignment film material with ultraviolet rays having a high degree of polarization. The quartz plate absorbs almost no ultraviolet rays, so the transmittance is large, and the loss of irradiation intensity due to polarized light is close to the ideal 50%. With these characteristics, by using this polarizing element as an ultraviolet polarizing device for liquid crystal alignment treatment, irradiation energy necessary for liquid crystal alignment can be obtained in a short time, and the alignment order of the liquid crystal can be increased.
[0046]
The embodiment of the present invention described above can be further modified based on the technical idea of the present invention.
[0047]
For example, the number of laminated quartz plates used, thickness, size, shape, etc., spacer shape, size, ultraviolet wavelength, alignment film material, etc. may be variously changed, and other components of the polarizing element or device You may change similarly about. Instead of the quartz plate, another light transmitting plate can be used.
[0048]
Further, the liquid crystal element to which the present invention can be applied is not limited to the above-described one (for example, a simple matrix method), but may be an active matrix method using a TFT, and an alignment control film that does not require rubbing is provided. Has the advantage of
[0049]
【The invention's effect】
In the present invention, as described above, a plurality of translucent plates are arranged with a predetermined gap therebetween, and light is incident from the side of one translucent plate at a Brewster angle or almost a Brewster angle, and the other translucent plate is transmitted. Since the polarized outgoing light is obtained from the plate side, it is possible to increase the ratio of the target polarization component while repeating the transmission and reflection of the incident light by the plurality of light transmission plates. Therefore, incident light can be efficiently polarized, and outgoing light with a sufficient degree of polarization can be obtained even with a large area. By irradiation with this polarized outgoing light, a polymer film with a large area is sufficient for liquid crystal alignment. It becomes possible to process so that it will be in a proper state.
Then, a plurality of substrates with the liquid crystal alignment film subjected to the polarization treatment are arranged to face each other so that the alignment treatment direction is antiparallel to the substrate facing surface, and the liquid crystal is sealed in this state. The liquid crystal molecules can be aligned in a highly ordered manner with a uniform pretilt angle in one direction.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a polarizing method and a polarizing element according to the present invention.
FIG. 2 is a schematic view of a comparative polarizing element.
FIG. 3 is a schematic view of a method and apparatus for producing a liquid crystal alignment film according to the present invention.
FIG. 4 is a schematic cross-sectional view of an example of a liquid crystal element manufactured according to the present invention.
[Explanation of symbols]
1 ... Non-polarized UV, 1C, 1D ... UV with sufficient degree of polarization, 2 ... Lens,
3 ... quartz plate, 4 ... spacer, 5 ... quartz polarizing element, 6 ... alignment film, 7 ... substrate,
8 ... quartz plate, 9 ... air layer, 10 ... quartz plate, 11 ... mercury lamp,
θ ₁ ... Incident angle (Brewster angle)

Claims (3)

In a method of manufacturing a liquid crystal element in which an electrode and a liquid crystal alignment film are respectively formed in this order on opposing surfaces of a plurality of substrates facing each other, and liquid crystal is sealed between the opposing surfaces.
A polarizing element comprising a plurality of light transmitting plate disposed together with a predetermined gap to face the polymer film on the front Symbol electrodes of said substrate,
Of the plurality of light transmitting plates, light is incident at a Brewster angle or almost a Brewster angle from one light transmitting plate side, and polarized outgoing light is obtained from the other light transmitting plate side,
A liquid crystal alignment film to form the emitted light is irradiated to the polymer membrane,
The a plurality of substrates with a liquid crystal alignment film, the alignment direction so that opposed to so that Do antiparallel with the opposing surface,
In this state, the liquid crystal is sealed
A method for producing a liquid crystal element . Wherein the spacer is provided in a plurality of light-transmitting plates, held constant or nearly constant at least the light incidence region and the light emission region of the gap, the method of manufacturing the liquid crystal device according to claim 1. A plurality of quartz plates which transmits ultraviolet rays is arranged in parallel or substantially in parallel, is incident polarized ultraviolet light as the light, to obtain a linearly polarized UV, a method of manufacturing a liquid crystal device according to claim 1.

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